This invention relates generally as indicated to an inflatable airfoil device and, more particularly, to an airfoil device which inflates to one shape to perform a lift-enhancing function during take-off/landing and which inflates to another shape to perform a deicing function during flight.
The wings of an aircraft are designed to provide sufficient lift and to minimize drag. A high camber allows an aircraft to operate at lower take-off and landing speeds and thus operate on runways of reduced distances. Also, a relatively blunt leading edge ensures that the air will flow smoothly over the wing""s topside during low speed flight. In contrast, during high speed flight, a low camber and a sharp leading edge translate into less drag and faster speeds for a given thrust-producing capacity. During high speed flight, ice may accumulate on the wings which can cause increased drag and, perhaps more significantly, reduced lift capacity of the affected wing whereby it is important that this ice be removed.
The present invention provides an airfoil device which inflates to one shape to perform a lift-enhancing function and which inflates to another shape to perform a deicing function.
More particularly, the present invention provides an airfoil device for attachment to the wing of an aircraft. The airfoil device has a chamber which is inflatable to provide a lift-enhancing airfoil geometry to the wing and other chambers which are inflatable to provide deicing forces to remove ice accumulation on the wing. The lift-enhancing chamber is shaped to provide, when inflated, an airfoil geometry with a higher camber and less sharp leading edge. The deicing chambers overlie the lift-enhancing chamber and the the inflated deicing chambers form a suitable arrangement (e.g., spanwise rows or a dimpled matrix) from the top margin to the bottom margin of the airfoil device.
The airfoil device can be made of a series of layers, including chamber-defining layers which define the lift-enhancing chamber and the deicing chamber. For example, the device can comprise a lift chamber-defining layer made of a non-stretchable material, another lift chamber-defining layer made of a stretchable material, a deicing chamber-defining layer made of a stretchable material, and another deicing chamber-defining layer also made of a stretchable material. The lift chamber-defining layers are joined together to define the lift-enhancing chamber and the deicing chamber-defining layers are joined together to define the deicing chambers. A base layer, adapted to be secured to the wing, can be bonded to the innermost lift chamber-defining layer and a cover layer, made of an extensible material, can be bonded to the outermost deicing chamber-defining layer.
When the airfoil device is installed to the wing of an aircraft, it will closely conform to the wing""s airfoil geometry when the lift-enhancing chamber and the deicing chambers are in a deflated condition. Thus, if the wing has an airfoil geometry with a low camber and a sharp leading edge, this geometry can be maintained during high speed flight when deicing is not necessary. However, when the lift-enhancing chamber is inflated, an airfoil geometry will be provided which has a higher camber and less sharp leading edge for low speed flight. Specifically, for example, the inflated lift-enhancing chamber could have a smooth rounded shape which translates gradually into a topside and an underside of the wing, with a major portion of the shape being positioned below the leading edge of the wing.
During operation of the aircraft, the lift-enhancing chamber is inflated to enhance lift and the deicing chambers are inflated to remove ice accumulation. The deicing chambers are maintained in a deflated condition during inflation of the lift-enhancing chamber and the lift-enhancing chamber is maintained in a deflated condition during inflation of the deicing chambers. The lift-enhancing chamber can be inflated during take-off and/or landing and the deicing chambers can be inflated between take-off and landing. For example, if ice accumulates on the wing during high speed flight, the deicing chambers can be repeatedly inflated and deflated until ice is removed from the wings of the aircraft.